Majority of US Patients Still Discharged on High-Dose Aspirin After Acute MI

Download this article's Factoid (PDF & PPT for Gold Subscribers)


In a recent 4-year period, most patients with an acute myocardial infarction (MI) treated in the United States were discharged on high-dose aspirin, according to a study published online August 12, 2014, ahead of print in Circulation: Cardiovascular Quality and Outcomes. This practice conflicts with guidelines updated since the study period endorsing low doses. 

“These findings suggest that large-scale educational efforts are needed to change US practice patterns regarding aspirin dosing post-MI,” write study coauthor Sandeep Das, MD, MPH, of the University of Texas Southwestern Medical Center (Dallas, TX), and colleagues. 

Methods
To look at aspirin dosing patterns in a contemporary cohort, the researchers examined data on 221,199 patients with an acute MI (40.2% with STEMI) who were discharged from 525 US hospitals participating in the National Cardiovascular Data Registry’s Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With The Guidelines (ACTION Registry-GWTG) from January 2007 to March 2011.


High-Dose Aspirin Frequent

Most patients (60.9%) were discharged with a prescription for high-dose aspirin (325 mg), 35.6% were discharged on low-dose aspirin (81 mg), and the rest received other doses. The proportion receiving high-dose aspirin did not change over time. 

High-dose aspirin was given more frequently to patients who had undergone PCI compared with those who were treated medically (73.0% vs 44.6%), which is consistent with ACC/AHA recommendations in place at the time. However, only 47.8% of patients who had undergone CABG were discharged on high-dose aspirin, even though the recommendations endorse higher doses in these patients.

The prescription of high-dose aspirin was common in certain high-risk groups of patients including those taking triple therapy with aspirin, a thienopyridine, and warfarin at discharge (44.0%) and those who had suffered a major bleed at the hospital (56.7%). 

After multivariate adjustment, treatment with any PCI was the strongest factor associated with the use of high- rather than low-dose aspirin. The association was seen for ]:

 

  • Angioplasty alone (OR 2.21; 95% CI 2.09-2.33)
  • BMS (OR 2.98; 95% CI 2.87-3.08)
  • DES (OR 3.06; 95% CI 2.96-3.16)

 

Several other factors were associated with reduced likelihood of receiving a prescription for high-dose aspirin including older age, female sex, a history of congestive heart failure, and concurrent use of warfarin, a thienopyridine, or both. 

Additionally, there was a 25-fold variation in the proportion of patients discharged on high-dose aspirin across centers, suggesting that “that local physician- or hospital-level practice habits, rather than individualized patient risk/benefit estimation, are the more important factors influencing aspirin prescribing patterns,” according to the authors.

Guidelines Then and Now  

During the study period, US guidelines indicated a preference for higher doses of aspirin for secondary prevention after an acute MI. “I think the aspirin dosing we observed was largely influenced by the PCI guidelines prior to 2012,” lead author Hurst M. Hall, MD, also of the University of Texas Southwestern Medical Center, told TCTMD in a telephone interview. 

However, between 2011 and 2013, the American College of Cardiology and American Heart Association updated the MI and PCI guidelines on the basis of data from both observational and randomized studies showing that lower aspirin doses were associated with similar efficacy but reduced risk of bleeding compared with higher doses.

“Each of these US guidelines now has a class IIa recommendation favoring 81 mg of aspirin over higher dosages,” the authors write. 

They suggest that their data reflect “a substantial gap” in the United States between accumulated data, practice guidelines, and aspirin dosing patterns. “Simply stated, postacute coronary syndrome patients should no longer be prescribed high-dose aspirin at discharge, regardless of the approach to PCI,” the researchers comment 

Moving Forward  

Dr. Hall said that while updates to the guidelines are unlikely to completely address the extensive use of high-dose aspirin, there is still room for improvement, particularly for high-risk patients such as those who have bleeding events in the hospital and who are taking other antiplatelets. 

He acknowledged that dosing patterns are unclear since the recommendations were changed but added, “I think even in today’s world of more complex anticoagulation strategies there is some remaining uncertainty out there about which doses of aspirin to use. 

“High-dose aspirin use is still very prevalent in the United States in contrast to other parts of the world,” Dr. Hall concluded. “I think that a very conscious decision needs to be made regarding aspirin dosing, in particular in patients who are on other forms of blood thinners or antiplatelet medications.”

 


Source: 
Hall HM, de Lemos JA, Enriquez JR, et al. Contemporary patterns of discharge aspirin dosing after acute myocardial infarction in the United States: results from the National Cardiovascular Data Registry (NCDR). Circ Cardiovasc Qual Outcomes. 2014;Epub ahead of print.

 

 

 

Related Stories:

Todd Neale is the Associate News Editor for TCTMD and a Senior Medical Journalist. He got his start in journalism at …

Read Full Bio
Disclosures
  • ACTION Registry-GWTG is funded in part by an independent grant from Bristol-Myers Squibb and Merck. This research was supported by the American College of Cardiology Foundation’s NCDR.
  • Drs. Das and Hall report no relevant conflicts of interest.

Comments